Clutter is a Microsoft Outlook feature that attempts to help you filter low-priority emails, saving time for your most important messages. The email server keeps track of the email you read and the ones you don't. Clutter is automatic. As a new email comes in, it takes messages you're most likely to ignore and puts them into the "Clutter" folder. The more you use it, the better it gets. And if you find Clutter isn't for you, you can turn it off.
In Outlook, right-click the Clutter folder and select Manage Clutter. (If you don't see the Manage Clutter option, Clutter may have been disabled for your organization or you may be using Focused Inbox now. See the next section for more options.)
Sign in to Outlook on the web using your work or school account. For help, see Sign in to Outlook on the web.
This will take you directly to the Clutter options page.
Either uncheck the box Separate items identified as clutter or select the option Don't separate items identified as Clutter depending on which option you see on the Clutter options page.
Click Save to turn off Clutter.
The Clutter folder remains in Outlook even after you turn off the feature.
Sign in to Outlook on the web. For help, see Sign in to Outlook on the web.
At the top of the page, select the App launcher > Outlook.
At the top of the page, select Settings, and under Your app settings, select Mail.
Under Automatic processing, select Clutter.